Variable capacity pump



y 27, 1958 M. NAVARRO 2,836,120

VARIABLE CAPACITY PUMP Filed Sept. 14, 1954 IE 1 I? E 3 I 7 United States atent O VARIABLE CAPACITY PUlVIP Miguel Navarro, Buenos Aires, Argentina Application September 14, 1954, Serial No. 455,868

2 Claims. (Cl. 103-38) This invention relates to variable output fluid pumps, and more particularly is directed to an improved variable output fluid pump adapted for use in hydraulic transmissions wherein the variable output pump is driven and the pumped fluid coming therefrom is used to drive a device, for example, a turbine, at a speed which is determined by the variable rate of output of the pump.

An object of this invention is to provide a pump of the described character wherein the output thereof, and hence the speed of the device driven thereby, may be conveniently varied independently of the speed at which the pump is driven.

in accordance with an aspect of the invention, a pump of the described character comprises a circular body delining a central admission chamber for the fluid to be pumped and having a plurality of cylinders opening radially from the admission chamber and each accommodating a radially movable piston, a drive shaft extending axially through the admission chamber and having eccentrics mounted thereon, each eccentric having a radial cylinder therein slidable on a tubular extension projecting radially from the drive shaft to adjust the eccentricity of the eccentric relative to the axis of the drive shaft, connecting rods pivotally connected between the pistons and collars on the eccentrics sothat the pistons are reciprocated in the related cylinders in response to rotation of the drive shaft, the drive having an axial bore or cavity communicating by way of the tubular extension with the radial cylinder of each eccentric, a plunger movable axially in the axial bore of the drive shaft to vary the pressure of a hydraulic fluid in the axial bore, and thereby to adjust the eccentricity of each eccenrtic, and a spindle screwed into the axial bore of the drive shaft and joined to the plunger so that the latter is axially displaced in response to rotation of the spindle relative to the drive shaft.

The above, and other objects, features and advantages of the invention, will be apparent in the following detailed description of an illustrative embodiment thereof which is to be read in connection with the accompanying drawing forming a part hereof, and wherein:

Fig. 1 is a sectional view of a pump embodying this invention taken along the line A-A of Fig. 2; and

Fig. 2 is a sectional view taken along the line B-B of Fig. l.

The pump mechanism according to the invention comprises: a circular pump body 1 having a circular central opening 2 (Figures 1 and 2) which defines an admission chamber for the fluids which are to be displaced. The body 1 further has radially directed bores 4 opening outwardly from the central opening 2 and arranged in two groups which each include three equally angularly spaced apart bores, with the bores 4 of one group lying in a plane which is parallel to, and spaced from the plane of the bores in the other group, as shown in Fig. 1. A piston 3 is slidable in each of the bores 4 of the body 1.

Admission chamber 2 is closed at the opposite axial 2,836,120 Patented May 27, 71958 ice.

2 ends thereof by means of individual covers 5 which are fixed and hermetical seals to the opposite faces of pump. body 1.

Radial chambers or bores 4 open at the external periphery of pump body 1 through respective orifices 6, which are formed in the interal periphery of an annular body 7 which forms an annular distribution chamber 8 into which fluid is pumped from the chambers 4 for supply, by way of a pipe 10, to a device, for example, a turbine, adapted to be driven by the pumped fluid, the pumped fluid is returnedfrom such turbine or the like, to the admission chamber 2 by way of another pipe (not shown).

Pistons 3 have respective gate valves 12 in the heads thereof which regulate the communication between the portions of chambers 4 disposed radially inward and outward with respect to the pistons. In the same fashion, orifices 6 have corresponding gate valves 13 associated therewith to regulate the communication between distributing chamber 8 and radial chambers 4. The functional relation between valves 12 and 13 is inversely reciprocal, that is, the open cycle of each valve 12 corresponds to the closed cycle of the related valve 13, and vice versa.

Covers 5 which close the opposite ends of admission chamber 2 have, at the geometrical centers of their external faces, individual hubs 14 through which project the end portions of a propulsion shaft 15 which is adapted to be connected to a prime mover, for example, an automotive or other vehicle engine or a stationary power plant. In the present instance, and as an illustrative example, the mechanism is intended for mounting on the frame of bicycles. When so used, the opposite ends of shaft5 carry crank pedals 16 by means of which the shaft 15 can be manually rotated Within bearings '17 which mount the shaft in the hubs 14.

Shaft 15 has, on the portion thereof which operates in admission chamber 2, a series of three circular axially spaced apart partitions 18 which form guides for the alternative oscillatory play of eccentric disks 19 disposed therebetween. .Said eccentric disks each have a circular opening 20, which is eccentrically located with respect to the center of the disk 19. The diameter of 'said openings 20 is calculated in proportion to the maximum stroke required for pistons 3 which are connected to said eccentric disks by means of individual connecting rods 21 pivotally connected, at their opposite ends, to the related pistons and to the external periphery of respective collars 22 mounted on the periphery of said eccentric disks 19.

Eccentric disks 19 each have, adjacent one of the diameters thereof individual radially directed cavities 23 and 24 which are axially aligned with each other. Cavities 23 form spaces which contain a hydraulic charge in viscous condition, whereas cavities 24 form spaces wherein helical compression springs 25 are lodged. The ends of said springs are seated freely against the bottom of said cavities 24 and radially against the shaft 15.

With further reference to eccentric disks 19, said disks are connected with a free alternative oscillatory play to tubular casings 26 which extend radially from shaft 15 and are slidably received in cavities 23 of said eccentric disks. Said radial casings 26 form passages of intermediate communication between cavities 23 and an axial cavity 27 in the shaft 15 extending along virtually the two thirds of the total length thereof. This cavity 27 forms a space which is entirely filled by the hydraulic charge as are also, the passages formed by radial casings 26 and cavities 23.

The hydraulic charge which fills cavity 27, the passages formed by radial casings 26 and cavities 23 operates as a regulating agentfor the stroke ofpistons- 3, depending upon the pressure to which said charge is subjected; whereby the length of stroke of the pistons, which is variable at will, varies With the pressure of the hydraulic fluid inicavity- 27. -Thus,; asthe pressure in cavity 27 is, increased, the eccentricityof disl s 19 is,- increased to increase the length of stroke of pistons 3 and, assuming I 'a constant rotational speed of the shaft 15,.to correspondingly increase the 7 rate at which fluid thedistribution-chamber 8. V v

As thevelocities toabe given to the objects, in conispumped from nectioniwith which. the. mechanism of the present, invention will be. applied, arev determined by the degree of compression of the hydraulic charge which exis'tsin cavity 27 of shaft 15, in'the radialv passage and cavity 23 of eccentric disks. 19', there'will be provided a regulating device for controlling the eompressionjof said hydraulic I :harge. -Thereg ulating device, comprises a spindle 28 whichcan. be adjusted by screwing. it more or less into adenlarged internally threaded cavity 27 which de- Y fines.-Jtheentrance.of cavity 27. Said spindle'28l has a stem 29 extending axially therefromwhi'ch forms a compressionmember or plunger for applying pressure to the hydraulic charge referred to, within predetermined limits which correspond to the desired variation in the length of stroke. of pistons 3. The spindle 2'8'connects to a fly-Wheel 30 provided at the marginal edge of one of the faces thereof with a plurality of teeth 31 by means the eccentricity of the related eccentric with respect to the axis of the drive shaft; means for adjusting the eccentricity'of each eccentric relative tdthe axisof the drive shaft comprising a radially directed tubular member extending from the drive shaft. for each eccentric, each eccentric having a radially inward opening cylinder therein receiving the related tubular member of the drive shaft, the drive'shaft having an axial bore opening at one end of the drive shaft and communicating with each radially directed tubular member, the open end portion of said axial bore having internal threads, an externally threaded spindle screwed into said internally threaded,

open end portion of the. axial b.ore,. and a plunger slidable in said axial bore and extending from said spindle of which. a rotatory movement in one sense or another may. be given to flywheel" 30 for transmission to spindle 28 until stem 29 provides a pressure of. the hydraulic charge which is required'to obtain the desired stroke of the pistons, ,1, I

I claim? '1'. In a pump having a circular body defining a cen tral' admission. chamber'f'or the fluid to be pumped'and at leastbne group of radial pump cylinders opening from the admission chamber into a'distribution'chamber surrounding the circular body with pistons reciprocable V in the radial pump cylinders. to pump fluid from the-admission chamber into thefdistributi'onchamber, a drive shaft extending axially through the" admission chamber, an eccentric on the drivesh'a'ft for each group of pump cylinders, andconn'ecting rodmeansjbetween the. pistons and. the relatedeccentric to. cause. reciprocationof'the pistons in response to rotation of the. drive shaft with the. length of stroke of, the pistons being determined by so that said plunger isfoperative to vary the pressure'on an hydraulic fluid filling said axial bore, each tubular member and the corresponding cylinder. of the related eccentric in response to turning of said spindle relative to the drive shaft, thereby to radially displace each eccentric relative to the axisof the drive shaft for varying the lengthof stroke of. the pump pistons. i

2.1m a pump; means for adjusting. the eccentricity of each eccentric relative to the axis of the drive shaft as in' claim .1, further comprising spring means acting radially between each eccentric and the'drive shaft to yieldably oppose the radial displacement of the related eccentric relative to the drive shaft caused by the action of hydraulic. fluidunder pressure ,in s'aid radially inward opening cylinder of the related eccentric, thereby to tend to center said eccentric relative to the drive shaft when-the pressure of the hydraulic fluid is decreased.

References Cited in the file of this patent- UNITEDSTATVES PATENTS 

